Transcript doc.: IEEE 802.1502/292r2 July, 2002 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [02292r2P802-15_TG3-SPS-Issue-Resolution.ppt] Date Submitted: [05 July, 2002 Source:

doc.: IEEE 802.1502/292r2
July, 2002
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [02292r2P802-15_TG3-SPS-Issue-Resolution.ppt]
Date Submitted: [05 July, 2002
Source: [Mark E. Schrader] Company [Eastman Kodak Co.]
Address [1447 Saint Paul St., Rochester, NY 14653-7023, USA]
Voice:[585-253-5241], FAX: [585-253-5658], E-Mail:[[email protected]]
Re: [Draft 10 Comment Resolution for Power Management and Stream Management.]
Abstract: [This supplements 02/231 in discussing proposed changes to D10]
Purpose: [Communciate changes to D10 proposed in 02/231 and use of changes by the network
members.]
Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for
discussion and is not binding on the contributing individual(s) or organization(s). The material in this
document is subject to change in form and content after further study. The contributor(s) reserve(s) the right
to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE
and may be made publicly available by P802.15.
Submission
Slide 1
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
SPS Issue Resolution
Channel Time Request and Stream
Management
Submission
Slide 2
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Outline
• In the context of the use of power
management:
– Proposed changes to CTRB and why.
– Proposed adjustments for superframe
loading control and documenting this
capability.
Submission
Slide 3
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Changes to CTRB
• Allow explicit choice of time base.
– Time Base bit selects between “CTR
Interval” field of CTRB and an “SPS Set”
for either CTR Type.
• PCTM setting in SPS.
– Set PCTM bit allows the source DEV to tell
the SPS DEV that it needs to listen to
every beacon and change to ACTIVE
mode.
Submission
Slide 4
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Octets: 1
1
2
2
2
1
1
1
1-127
1
Desired
Number
of TUs
Minimum
Number
of TUs
CTR
TU
CTR
Interval
CTR
Control
Stream
Index
Stream
Request
ID
SPS Set
Index
Target ID
List
Num
Targets
Figure 73 Channel Time Request Block
Bits: 7
1
1
1
1
1
1
3
Reserved
Set
PCTM
Time
Base
CTR
Interval
Type
GTS
Type
CTR
Type
Stream
Termination
Priority
.
Figure 94. CTR Control field in the Channel Time Request Block
Additions or Changes to Existing Strucures
Submission
Slide 5
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
CTR
Type
Time
Base
Set
PCTM
Destination
DEV’s PS mode
CTR
Interval Use
SPS
Set Use
Set PCTM
Bit?
ACTIVE
CTR
Interval
No
X
Slots per SF or
SFs per Slot
------
No
ACTIVE
CTR
Interval
Yes
SPS
Slots per SF or
SFs per Slot
------
Yes
ACTIVE
CTR
Interval
X
X
Slots per SF or
SFs per Slot
------
No
ACTIVE
SPS Set
X
X
------
SFs per Slot
No
SPS
CTR
Interval
X
X
SFs Per
Awake Beacon
------
No
SPS
SPS Set
X
X
Awake Beacons
per Slot
SFs Per
Awake Beacon
No
Inputs
Submission
Outputs
Slide 6
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Advantages of Changes
• There are 3 scenarios that need to be
covered by our standard
– 1. Active mode stream s1 created using
“CTR Interval” time base: Suspend the
stream s1 when switching to SPS mode.
• A high-data-rate communication cannot be
sourced by a DEV that has switched into SPS
mode.
• It will be begin again once the DEV has
switched back to ACTIVE mode from SPS
mode.
Submission
Slide 7
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Power Save Transitions
Affect on Stream s1 (see previous slide)
D2
D2
s1
D0
s1
ACTIVE Mode
SPS Mode
D0
Legend
Submission
Stream in Use
DEV in ACTIVE mode
Suspended Stream
DEV in SPS mode
Slide 8
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
– 2. ACTIVE mode DEV wants to talk to an
SPS DEV using SPS timing. The ACTIVE
DEV creates stream s2 using an “SPS Set”
as the time base. Stream s2 will continue
when ACTIVE DEV switches to SPS mode.
• An example is a power sensitive recording
device with wireless remote control.
• Remote control stays in SPS mode, Recording
device alternates between SPS and ACTIVE
mode.
• Alternating mode DEV must maintain link with
the SPS mode DEV, preferably without any
overhead communication to the PNC.
Submission
Slide 9
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Power Save Transitions
Affect on Stream s2 (see previous slide)
D1
D1
s2
s2
D0
ACTIVE Mode
SPS Mode
D0
Legend
Submission
Stream in Use
DEV in ACTIVE mode
Suspended Stream
DEV in SPS mode
Slide 10
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
– 3. A DEV is in ACTIVE mode. The DEV
requests an SPS, CTR Type stream s3
using an “SPS Set” time base. s3 starts
out suspended. When the DEV switches
into SPS mode the stream s3 starts up.
• Application space: A DEV wants to
synchronously communicate with other SPS
DEVs in a power sensitive application.
• The application is exclusively for SPS mode.
• When the DEV switches back to ACTIVE mode
the stream s3 is suspended.
Submission
Slide 11
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Power Save Transition
Affect on Stream s3 (see previous slide)
D0
ACTIVE Mode
SPS Mode
s3
D0
s3
D3
D3
Legend
Submission
Stream in Use
DEV in ACTIVE mode
Suspended Stream
DEV in SPS mode
Slide 12
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
– 4. The same as 3 except that the DEV
uses a “CTR Interval” time base rather
than the “SPS Set” time base.
• This is an example of a DEV that wants to save
power without any data communication, and
idle power save condition.
• The “CTR Interval” is used as the time base to
avoid wasting an SPS Set when no
synchronization is required.
• This “stream” only has awake beacons, no GTS
slots.
Submission
Slide 13
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Power Save Transitions
Affect on Stream s4 (see previous slide)
ACTIVE Mode
SPS Mode
D0
D0
s4
Don't Care
Station
s4
Legend
Submission
Stream in Use
DEV in ACTIVE mode
Suspended Stream
DEV in SPS mode
Slide 14
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Power Save Transitions Summary
Affects on Streams s1, s2, s3 and s4 (see previous slides)
D1
D2
s2
s1
D2
s2
ACTIVE Mode
D0
s3
D1
SPS Mode
s4
D0
s3
D3
s1
s4
D3
Legend
Submission
Stream in Use
DEV in ACTIVE mode
Suspended Stream
DEV in SPS mode
Slide 15
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Proposed Addition to Standard
CTRB Parameters
Default Stream Management
CTR Type
Time Base
ACTIVE to SPS
Effect on Stream
SPS to ACTIVE
Effect on Stream
ACTIVE
CTR Interval
Suspend
Restore
ACTIVE
SPS Set
Continue
Continue
SPS
CTR Interval
Restore
Suspend
SPS
SPS Set
Restore
Suspend
Submission
Slide 16
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
APS and SPS After Changes
Convergence?
Submission
Slide 17
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
SPS/APS Overlap With Proposed Changes
• Combined SPS and APS major capabilities:
– 1. PCTM traffic indication.
– 2. Flexible listen-to-beacon schedule up to
a maximum.
– 3. Synchronous communication.
– 4. Predictable listen-to-beacon times.
– 5. Single DEV defines sleep duration.
• The only APS-unique capability left will be
number two in the list above. Is this close
enough to eliminate APS?
Submission
Slide 18
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Superframe Loading
Submission
Slide 19
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Concern: Superframe Loading
• Superframe loading is the number of GTS
slots allocated to a superframe
• Differential superframe loading is the ratio of
the largest number of GTS slots allocated to a
superframe to the smallest number of SF’s
allocated to a superframe. This can be
caused by a large number of DEVs using the
same SPS Set.
Submission
Slide 20
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Can there be some control over SF loading?
• Yes by noting that the maximum power save
always occurs if the SPS mode DEV’s awake
superframes only occur when a GTS slot is
needed.
• In this case any SPS DEV using the same
SPS Set to achieve the same GTS slot
allocation rate must have a slot in the exact
same super frame.
• For this case the CTR Interval is always “1”,
meaning “one awake beacon per Slot”.
Submission
Slide 21
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
SF Loading Control Continued
• What if the SPS Set is specified with a an
SPS interval that makes the SPS DEV wake
up 4 times as often as it needs a slot, then
the power saved is less and the possible
loading is less also.
• The next two charts show how the PNC may
allocate slots to distribute the loading.
• It is up to the SPS DEV to trade off
superframe loading for power.
Submission
Slide 22
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
awake beacon
assigned
GTS slot
Equivalent GTS Alloctations for
SPS Interval = 2 and CTR Interval = 4
Submission
Slide 23
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
1 2
3 4
5 6
7 8
1 2
3 4
5 6
7 8
Minimum Slot Loading GTS Alloctations for 8 DEVs Requesting
SPS Interval = 2 and CTR Interval = 4
Submission
Slide 24
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Changes Required to the Draft
– Include the two diagrams shown here to
show possible slot distribution by the PNC.
– Make the minimum number SPS Sets 2 in
order to facilitate an SPS DEV transitioning
from one SPS Set to another, when a large
number of DEVs have joined.
– Add an indication of “Superframe
Overloading” as a return code for a DEV
trying to allocate channel time and have
the PNC tell the SPS Set creator DEV if
necessary.
Submission
Slide 25
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
SPS Information Element
Use and Format Issues
Submission
Slide 26
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Power Save Mode Issues
• A DEV 1 may need to change its PS mode
without being able to communicate to all
DEVs that might be effected by the change.
• When should a DEV 2 inquire about the PS
mode of a DEV 1? There is no way to know.
• There is no guaranteed performance for
inquiring about the PS mode of a DEV 1.
• The St Louis compromise demanded that
ready access to the PS mode and SPS
information be available in the beacon.
Submission
Slide 27
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
What is the Minimum Information Required?
• The current format requires one IE for each
SPS Set that is “in use”, meaning that at least
one set member is currently in SPS mode.
• Both PS mode and SPS Set information is
required for DEV 2 to make the correct CTR
to the PNC.
• The structure of the SPS IE, should be
changed to be like that of the PCTM, but
otherwise not changed.
Submission
Slide 28
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Proposed Change
• The SPS IE should be in the same format as
the PCTM to limit its size.
• The SPS IE is necessary to allow DEVs to
make superframe by superframe decisions on
what CTRB parameters to use for effective
channel specification and changes that could
effect current CTRs in effect.
Submission
Slide 29
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
02263r0 Alternative Power Save Proposal
Submission
Slide 30
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Acronym for This Document: PSCI
• Power Save CTR Interval, PSCI, is defined as
a the CTR Interval associated with a CTRB
made with the new field defined in 02163r0:
“Use a single bit to indicate if the Channel
time request is a power save request or not.”
Submission
Slide 31
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Creating and Managing Unique PSCIs
• The PNC creates a unique (indexed) PSCI-1, PSCI2, etc. for each PSCI in a CTRB that::
• 1. Has a CTR Interval that no other PSCI has or
• 2. (for an identical CTR Interval) does not have
at least one DEVID in common with existing
PSCIs with the same CTR Interval.
– For each PSCI-n, the PNC must keep a list of both
the CTR Interval and PNIDs of streams that the
PNC has assigned to it.
– This is equivalent to PNC generated and
managed SPS Sets with no limits to the
number of sets.
Submission
Slide 32
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Differences
• One slot per wake beacon is the only
possibility.
• The DEVIDs are used by the PNC to
determine which existing PSCI-n will be used
or if a new PSCI-k will be created.
• PNC controls
Submission
Slide 33
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
The order of stream creation matters
D1
s1
PSCI 1
s2
PSCI 1
D3
D2
s3
PSCI 1
D0
s7
PSCI x ?
D6
s5
PSCI 2
D4
s4
PSCI 2
D5
s6
PSCI 2
D7
Submission
Slide 34
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Notes on the Previous Figure
• D0, D1, D2, D3 uses PSCI-1 and D4, D5,
D6, D7 uses PSCI-2
• Devices D0, D1, D2, D3 and D4, D5, D6, D7
cannot have sychronized timing because of
the sequence of stream creation.
• Result: D0 and D7 do not achieve their power
save goals. If PSCI-1 and PSCI-2 are very
different, the power saving of one of these
devices could be impacted significantly.
• A DEV must create its first stream with a set
in the PSCI-k that it ultimately wants to use.
Submission
Slide 35
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Appendix
Submission
Slide 36
Mark Schrader, Eastman Kodak Co.
doc.: IEEE 802.1502/292r2
July, 2002
Time
Base
CTR
Interval
Type
CTR
Interval
CTR
Interval
CTR
Interval
CTR
Interval
SFs per
Slot
SFs per
Slot
Slots per
SF
Slots per
SF
ACTIVE
SPS Set
SPS
SPS
CTR
Type
ACTIVE
ACTIVE
ACTIVE
ACTIVE
Set
PCTM
Destination
DEV PS
mode =
CTR
Interval Use
SPS
Set Use
Set
PCTM
Bit?
OFF
X
SFs per Slot
X
No
SPS
SPS
SFs per Slot
X
Yes
OFF
X
Slots per SF
X
No
SPS
SPS
Slots per SF
X
Yes
X
X
X
---
SFs per Slot
No
CTR
Interval
X
X
X
X
No
SPS Set
X
X
X
SFs per Wake
Beacon
No
SFs per Wake
Beacon
Wake Beacons
per Slot
A More Detailed Version of Slide 6
Submission
Slide 37
Mark Schrader, Eastman Kodak Co.